Warner-Lambert Company LLC v Generics (UK) Ltd (trading as Mylan) and Others

Heard on 12, 13, 14 and 15 February 2018

( with whom Lord Reed agrees)

These proceedings raise, for the first time in the courts of the United Kingdom, the question how the concepts of sufficiency and infringement are to be applied to a patent relating to a specified medical use of a known pharmaceutical compound. An important objective of modern pharmaceutical research is the discovery of new medical uses for known molecules. This commonly involves expensive research programmes, which will not be rewarded and will therefore not happen unless patent protection is available. Patent protection for second use medical patents is, however, difficult to accommodate within the traditional scheme of patent law. Traditionally, there were two legal obstacles. First, both the product and the process by which it was prepared were known from the original patent and therefore failed the test of novelty. Secondly, its use for a new therapeutic purpose was not itself patentable because article 52(4) of the European Patent Convention (the “EPC”) and section 4(2) of the UK Patents Act 1977 prevented the grant of patents for a method of treatment of the human or animal body.

As is now well known, in 1984 the Swiss Federal Intellectual Property Office issued a statement of practice that it would be prepared to grant patents for second use medical patents in the following form: “the use of compound X in the manufacture of a medicament for the treatment of indication Y”: [1984] OJ EPO 581. Hence the expression “Swiss-form patents” for patents granted in this form. The Enlarged Board of Appeal of the European Patent Office adopted this approach shortly afterwards in EISAI/Second Medical Indication G 05/83 [1979–85] EPOR B241. It ruled, at para 23, that it was

“legitimate in principle to allow claims directed to the use of a substance or composition for the manufacture of a medicament for a specified new and inventive therapeutic application, even in a case in which the process of manufacture as such does not differ from known processes using the same active ingredient.”

Swiss-form patents were not product patents, but purpose-limited process patents. They surmounted both obstacles because the invention is identified as neither a product nor a method of treatment but a manufacturing process for a novel purpose.

This development responded to a real problem, namely the difficulty of obtaining patent protection for second uses that may have been truly inventive and involved costly research. But it has given rise to formidable analytical problems as a result of the need to apply to Swiss-form patents a statutory scheme which was not designed to accommodate them. For this reason they were regarded with suspicion as intellectually impure by patent lawyers in the United Kingdom. In John Wyeth and Brother Ltd's Application [1985] RPC 545, they were adopted with express misgivings by the Patents Court in the interests of uniformity among states party to the EPC. But in spite of the misgivings, they have achieved a secure place in United Kingdom patent law, and neither party to this appeal challenges them in principle. Some of the difficulties associated with them were resolved when the EPC was revised in November 2000 to provide for (among other things) the grant of purpose-limited product patents: see article 54(5) of the revised Convention. Corresponding changes were made to the Patents Act 1977 by the Patents Act 2004. Once these changes came into effect, in 2011, Swiss-form patents ceased to be issued by the European Patent Office. EPC 2000 patents give rise to difficulties of their own, some of which are very similar. But this appeal is not concerned with them.

Warner-Lambert is a company in the Pfizer Group. It is the proprietor of European Patent No 0641330 for Isobutylgaba for the treatment of seizure disorders, notably epilepsy. Pregabalin is a derivative of Isobutylgaba, which is also referred to by its chemical name (S)-3-(aminomethyl)-5-methylhexanoic acid. It is marketed by Warner-Lambert under the brand name “Lyrica”. Patent No 0641330 expired in the United Kingdom on 17 May 2013.

The present appeal concerns a second European Patent, EP(UK) No 0934061, entitled “Isobutylgaba and its derivatives for the treatment of pain”, with a priority date of 24 July 1996 (“the Patent”). The claims of the Patent are all purpose-limited. Those which are principally relevant are Claims 1, 2 and 3, which are in the following terms:

“1. Use of (S)-3-(aminomethyl)-5-methylhexanoic acid or a pharmaceutically acceptable salt thereof for the preparation of a pharmaceutical composition for treating pain.

2. Use according to Claim 1 wherein the pain is inflammatory pain.

3. Use according to Claim 1 wherein the pain is neuropathic pain.”

It is common ground that the skilled person to whom the Patent is deemed to be addressed is a team consisting of a neuroscientist and a clinician specialising in the treatment of pain. To explain what the skilled team would understand by the terms used in the claims, it is necessary to say something about what was known at the priority date about the physiology of pain.

The second edition of Classification of Chronic Pain Syndromes and Definitions of Pain Terms, published in 1994 by the International Association for the Study of Pain, defined “pain” very broadly. It is “an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage.” At the priority date, pain was classified into a number of different types. The distinctions between them were neither absolute nor consistently understood. But it was generally recognised that pain fell into two broad categories: nociceptive and neuropathic pain.

Nociceptive pain is produced by noxious external stimuli such as heat, extreme cold, intense mechanical pressure or chemicals. These stimuli stimulate fibres known as nociceptors, which transmit impulses via the spinal cord to the brain, where they are perceived as pain. Nociceptive pain has a bio-protective function. It alerts the brain to the presence of noxious stimuli so that appropriate avoidance measures can be taken. This type of pain resolves with treatment of the underlying cause.

Inflammatory pain is a type of nociceptive pain. The body's response to an injury involves the release of chemical mediators which increase the sensitivity of nociceptors causing pain both at the site of the injury or in the surrounding area. Like other nociceptive pain, inflammatory pain resolves with the treatment of the underlying cause. In 1996, well known and efficacious treatments were available for treating inflammatory pain. They included analgesics (eg paracetamol), non-steroidal anti-inflammatory drugs (eg aspirin, ibuprofen) and opioids of various strengths.

Neuropathic pain, unlike nociceptive/inflammatory pain, is pathological. It has no bio-protective function. It is caused by damage to the nervous system itself. Neuropathic pain was defined in the second edition of the IASP's Classification of Chronic Pain as “pain initiated or caused by a primary lesion or dysfunction of the nervous system.” The nervous system comprises the central nervous system, ie the brain and spinal cord, and the peripheral nervous system, ie the nerves outside those structures. Critical to the issues in these proceedings is the distinction between peripheral neuropathic pain, which arises from damage or dysfunction of the peripheral nervous system; and central neuropathic pain, which is rarer and arises from damage or dysfunction of the central nervous system, for example as a result of a stroke, multiple sclerosis or spinal cord injury. The symptoms of neuropathic pain (of either kind) are more severe than those of nociceptive/inflammatory pain. They include perceptions of burning, shooting pain and electric shock pain. Moreover, unlike nociceptive/inflammatory pain, neuropathic pain is persistent, sometimes for years or for life. It was in 1996, and still is, notoriously difficult to treat neuropathic pain. In particular, treatments which were efficacious against nociceptive/inflammatory pain, such as non-steroidal anti-inflammatory drugs, were not regarded as...